Field of the Invention
The invention relates to a sheet guiding device assemblable from a first sheet guiding element and a second sheet guiding element, for guiding sheets of printing material in a sheet-fed printing press.
In sheet-fed printing presses, sheet guiding devices are used for smear-free transport of sheets of printing material. In this regard, the sheets of printing material, during the transport thereof, slide directly on sheet guiding elements, or on a blown air cushion generated on the sheet guiding elements, so that the sheets of printing material are held, for example, at the circumference of a transport drum that transports them. In this manner, cardboard or pasteboard sheets of high flexural strength can be transported very reliably. Such sheet guiding devices must be cleaned at regular intervals to remove smeared-off printing ink and paper dust adhering thereto.
In the German Utility Model DE 297 10 252 U1, a guiding device for sheet-type printing materials or printing stock is described, the guiding device having a continuous surface formed by a plurality of guide baffles. A guide can also be provided, in which a guide baffle is braced so as to be able to exercise a thrusting or sliding movement. A hinge-type swivel joint can also be braced on the guide. Alternatively, the guide can be formed, on the frame side, as a groove in which the guide baffle slides with a thrusting movement through the intermediary of bolts.
In the aforedescribed device of the prior art, the guide baffles are supported in swivel joints fixed to the frame. The guide baffles are not assemblable, nor is the guide constructed accordingly. With this guiding device, good accessibility to the sheet guiding cylinder is indeed attained, but maintenance of the guiding device itself involves complicated and expensive dismantling work. For thorough cleaning of the guiding device, it is advantageous for it to be removable from the printing press. This is possible here only if the hinges are loosened by tools, which in practice is very time-consuming. The guiding device is assigned to the middle one of three serially arranged sheet-guiding cylinders, and is disposed thereabove. The guiding device is structurally unsuitable for a disposition in the region below the sheet guiding cylinder, and thus cannot be used for printing presses in which there is only a single sheet transfer drum between the impression cylinders of two printing units. In that case, due to the direction of rotation of the sheet transfer drum, the sheet of printing material is in fact transported by the sheet transfer drum underneath the latter. The described guiding device is indeed especially well suited to bending-resistant materials, but is less well suited for thin, unstable printing materials.
In German Utility Model DE 295 01 537 U1, there is described a sheet guiding device with air supply chests or cases, which is the closest prior art to the invention. The sheet guiding device can be disposed below a transfer drum which, as the only drum, transports the sheet of printing material between two printing units and the impression cylinders thereof. The guide surfaces of the sheet guiding device are assemblable from modules. The modules are assembled during the erection of the printing press. No guidance is provided for facilitating a simple and rapid assembly and disassembly of the modules. The printing press must be partly dismantled and the transfer drum must be removed because the sheet guiding device is otherwise not accessible for cleaning.